Toxicity of Chlorinated Biphenyls

Abstract

Despite the fact that polychlorinated biphenyls (PCBs) have been available commer­ cially for 40 years, it is only within the last 5 years that they have been recognized to be of environmental and potential toxicologic concern. PCBs are produced by a comparatively small number of manufacturers in the USA, France, Germany, and Japan and marketed under a number of commerical trade names, e.g. ArocIor, Clophen, PhenocIor, and KanecIor. The series of ArocIors (Monsanto) are marketed under various numbers and consist of mixtures of chlorinated biphenyls and terphenyls. The first two digits represent the molecular type: 12-chlorinated biphenyls; 25 and 44-blends of chlori­ nated biphenyls and chlorinated terphenyls (75% biphenyl and 60% biphenyl, respectively); 54-chlorinated terphenyls. The last two digits give the weight percent of chlorine, e.g. Aroclor 1242 is a chlorinated biphenyl containing 42% chlorine. The PCBs have been employed in a broad spectrum of applications because of their chemical stability, low volatility, high dielectric content, non flammability, and general compatability with chlorinated hydrocarbons. The major areas of utility include: heat exchanger and dielectric fluids, hydraulic and lubricating fluids, plasti­ cizers for plastics and coatings, ingredients of caulking compounds, printing inks, paints, adhesives, and carbon less duplicating paper, flame retardants, and extender for pesticides. The rates and routes of transport of the PCBs in the environment (I), and their accumulation in ecosystem (2-16), have been cited. Salient features of the chemical (3,4,7, 11, 14-17), analytical (3-18), biological (3,7,9, 14-20,28,30-38), aspects of the PCBs as well as their occurrence in human diets (2-4, 14, 15, 39-42), and tissue (14-16, 33-38, 43-47), have all been reported. The major objective of this review is to highlight the status of the toxicologic, carcinogenic, teratogenic, and mutagenic aspects of the PCBs that are of greatest relevance to man. Compared to the chlorinated hydrocarbon pesticides, definitive aspects of acute, subacute, and chronic toxicity still remain rather poorly known. The toxicological